Vehicle body rear structure

ABSTRACT

A vehicle body rear structure includes: a pair of left and right rear side frames extending in a fore-and-aft direction in a rear part of a vehicle; a rear subframe attached to the rear side frames; and a pair of left and right shock-absorbing structures respectively provided at rear ends of the rear side frames and extending rearward. The rear subframe includes a pair of left and right rear subframe longitudinal members extending in the fore-and-aft direction and a rear subframe cross member extending laterally and joined to the left and right rear subframe longitudinal members. The rear subframe cross member includes a protrusion that protrudes rearward in a laterally central part thereof. A rear end of the protrusion is positioned more rearward than the rear ends of the rear side frames and more forward than rear ends of the shock-absorbing structures.

TECHNICAL FIELD

The present invention relates to a vehicle body rear structure includinga rear subframe.

BACKGROUND ART

As a vehicle body rear structure of a four-wheel vehicle, there is knowna structure including a pair of left and right rear side framesextending in the fore-and-aft direction and a rear subframe attached tothe underside of the rear side frames (see JP2011-143871A, for example).The rear subframe supports an engine and a power generator and has afunction of dispersing or absorbing the collision load at the time of arear collision of the vehicle.

However, in the prior art structure, a load caused in a relatively lightrear collision is transmitted to the rear subframe supporting the wheelsand the driving source, and the load transmitted to the rear subframemay cause deformation of the rear subframe. If the rear subframedeforms, it becomes difficult to continue to use the vehicle and a highrepair cost may become necessary. Therefore, it is desired that thecollision load is transmitted to the rear subframe when the collisionload is large, and the collision load is not transmitted to the rearsubframe when the collision load is small.

SUMMARY OF THE INVENTION

In view of the above background, a primary object of the presentinvention is to provide a vehicle body rear structure that can prevent aload in a rear collision from being easily transmitted to the rearsubframe when the load is small.

To achieve the above object, one embodiment of the present inventionprovides a vehicle body rear structure (1), comprising: a pair of leftand right rear side frames (71) extending in a fore-and-aft direction ina rear part of a vehicle (2); a rear subframe (72) attached to the rearside frames; and a pair of left and right shock-absorbing structures(130) respectively provided at rear ends of the rear side frames andextending rearward, wherein the rear subframe includes a pair of leftand right rear subframe longitudinal members (91) extending in thefore-and-aft direction and a rear subframe cross member (93) extendinglaterally and joined to the left and right rear subframe longitudinalmembers, the rear subframe cross member includes a protrusion (93L) thatprotrudes rearward in a laterally central part thereof, and a rear endof the protrusion is positioned more rearward than the rear ends of therear side frames and more forward than rear ends of the shock-absorbingstructures.

Thereby, the rear subframe cross member receives the load at theprotrusion thereof after the shock-absorbing structures absorb the load.Therefore, a relatively small collision load is absorbed by theshock-absorbing structures and is prevented from being easilytransmitted to the rear subframe. Thus, the deformation of the rearsubframe is suppressed. On the other hand, when the collision load islarge, the load is transmitted from the protrusion to the rear subframeso that the load applied to the rear side frames can be dispersed.

Preferably, each shock-absorbing structure includes a firstshock-absorbing member (131) extending rearward from the rear end of thecorresponding rear side frame and a second shock-absorbing member (132)extending rearward from the rear end of the corresponding rear sideframe and having a fore-and-aft strength higher than that of the firstshock-absorbing member, rear ends of the second shock-absorbing membersare positioned more forward than rear ends of the first shock-absorbingmembers, and the rear end of the protrusion is positioned more forwardthan the rear ends of the second shock-absorbing members.

Thereby, a relatively small collision load can be absorbed by the firstshock-absorbing members. On the other hand, when the collision load islarge, the load can be absorbed by the rear side frames and the secondshock-absorbing members.

Preferably, each first shock-absorbing member consists of a crash boxextending rearward from the rear end of the corresponding rear sideframe and having a rear end joined to a laterally extending bumper beam(133).

Thereby, the bumper beam can receive the load input from variouspositions on either lateral side of the vehicle rear end, and the loadinput to the bumper beam can be transmitted to the first shock-absorbingmembers.

Preferably, the vehicle body rear structure further comprises a drivingsource (75) for driving the rear wheels, the driving source beingmounted on an upper side of the rear subframe, wherein upper ends of theshock-absorbing structures are positioned higher than a lower end of thedriving source, and lower ends of the shock-absorbing structures arepositioned lower than an upper end of the driving source.

Thereby, the shock-absorbing structures positioned more rearward thanthe driving source can receive the load from the rear so that the loadis prevented from acting on the driving source.

Thus, according to one embodiment of the present invention, there isprovided a vehicle body rear structure that can prevent a load in a rearcollision from being easily transmitted to the rear subframe when theload is small.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bottom view of a vehicle body structure according to anembodiment of the present invention;

FIG. 2 is a bottom view of the vehicle body structure with a frontsubframe and a rear subframe being omitted;

FIG. 3 is a side view of a front part of the vehicle body structure;

FIG. 4 is a bottom view of the front part of the vehicle body structure;

FIG. 5 is a perspective view of the front subframe;

FIG. 6 is a left side view of the front subframe;

FIG. 7 is a sectional view showing a fastening structure between a rearend portion of a front longitudinal member of the front subframe and arear-end support;

FIG. 8 is a plan view showing the front subframe;

FIG. 9 is a perspective view showing a connecting structure between therear side frame, the vehicle body cross member, and a load transmittingmember, with a rear floor panel being omitted;

FIG. 10 is a sectional view showing the connecting structure between therear side frame, the vehicle body cross member, and the loadtransmitting member;

FIG. 11 is a perspective view of the rear subframe;

FIG. 12 is a plan view of the rear subframe;

FIG. 13 is a sectional view taken along line XIII-XIII in FIG. 12;

FIG. 14 is a rear view showing a left rear end of the rear subframe (aview as seen along arrow XIV in FIG. 12);

FIG. 15 is a perspective view showing the left rear end of the rearsubframe as seen from below;

FIG. 16 is a sectional view taken along line XVI-XVI in FIG. 12;

FIG. 17 is a sectional view taken along line XVII-XVII in FIG. 12;

FIG. 18 is a left side view of a rear part of the vehicle body structure(with a left sidewall of the rear side frame being omitted);

FIG. 19 is a perspective view showing a left end of the rear part of thevehicle body structure;

FIG. 20 is a cross-sectional view of a shock-absorbing structure co; and

FIG. 21 is an explanatory diagram showing an arrangement of an electricmotor in the rear part of the vehicle body structure.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

In the following, a vehicle body structure according to an embodiment ofthe present invention will be described. In the following description,the fore-and-aft direction, the lateral direction (vehicle widthwisedirection), and the vertical direction are defined with respect to thevehicle. “Laterally inward (vehicle widthwise inner side)” indicates adirection toward the center of the vehicle in the lateral direction, and“laterally outward (vehicle widthwise outer side)” indicates a directionaway from the center of the vehicle in the lateral direction. Theframes, panels, and other members constituting the vehicle bodystructure are made of steel unless otherwise mentioned.

As shown in FIGS. 1 and 2, the vehicle body structure 1 includes a pairof left and right side sills 3 extending in the fore-and-aft directionon either lateral side of a lower part of the vehicle 2, a pair of leftand right front side frames 4 extending in the fore-and-aft direction ina front part of the vehicle 2 and having rear ends connected to thefront ends of the respective side sills 3, and a front subframe 6attached to the underside of the front side frames 4 and supportingfront wheels 5.

A front floor panel 7 is provided on the upper side of the left andright side sills 3 so as to extend between the side sills 3 and has avertically facing surface. As shown in FIG. 3, a pair of left and rightfront pillars 8 are provided at the front ends of the left and rightside sills 3, respectively. Each front pillar 8 extends vertically andhas a lower end joined to the front end of the corresponding side sill3. As shown in FIGS. 1 and 2, a dash panel 9 is provided between theleft and right front pillars 8 so as to have a surface facing in thefore-and-aft direction. The dash panel 9 has left and right side edgesjoined to the left and right front pillars 8, respectively, and has alower edge joined to a front edge of the front floor panel 7.

As shown in FIGS. 1 to 4, the left and right front side frames 4includes front side frame front parts 4A extending in the fore-and-aftdirection at positions laterally inward of and above the left and rightside sills 3, front side frame middle parts 4B extending rearward anddownward from the rear ends of the respective front side frame frontparts 4A, and the front side frame inclined parts 4C (outriggers)extending rearward and laterally outward from the rear ends of therespective front side frame middle parts 4B and connected to the frontends of the corresponding side sills 3.

Each front side frame middle part 4B has a hat-shaped cross-sectionopening upward and is joined to a front face of a lower part of the dashpanel 9 so as to form a closed section structure in cooperation with thedash panel 9. Each front side frame inclined part 4C has a hat-shapedcross-section opening upward and is joined to a lower surface of thefront floor panel 7 so as to form a closed section structure incooperation with the front floor panel 7. Each front side frame inclinedpart 4C has a fore-and-aft width that increases gradually toward thelaterally outward direction and has a laterally outer end joined to alaterally inner surface of the corresponding side sill 3.

As shown in FIG. 3, a bulkhead 11 is provided at the front ends of thefront side frame front parts 4A. The bulkhead 11 includes a pair of leftand right bulkhead side members 11A extending vertically, a bulkheadupper member 11B extending laterally and connecting the upper ends ofthe left and right bulkhead side members 11A, and a bulkhead lowermember 11C extending laterally and connecting the lower ends of the leftand right bulkhead side members 11A, whereby the bulkhead 11 is formedin a rectangular frame shape. The front end of each front side framefront part 4A is joined to a vertically middle part of a rear surface ofthe corresponding bulkhead side member 11A.

A front bumper beam 13 extending laterally is attached to the left andright bulkhead side members 11A via left and right front crash boxes 12serving as shock-absorbing members, respectively. Each front crash box12 is formed in a tubular shape extending in the fore-and-aft direction,having a rear end joined to a vertically middle part of thecorresponding bulkhead side member 11A, and having a front end joined toa rear side of the front bumper beam 13. The front crash boxes 12 havefore-and-aft stiffness lower than that of the front side frames 4, thefront bumper beam 13, and the bulkhead 11, and when a load in a frontalcollision is applied thereto, undergoes deformation earlier than thefront side frames 4, the front bumper beam 13, and the bulkhead 11 toabsorb the impact.

An upper part of each front pillar 8 is provided with a front uppermember 15 which extends forward and then extends forward and downward.Each front upper member 15 is positioned laterally outward and above thecorresponding front side frame front part 4A. The front end of eachfront upper member 15 is joined to the front end portion of thecorresponding front side frame front part 4A via a laterally extendingconnecting member 16. Further, a front damper housing 17 is providedbetween the front side frame front part 4A and the front upper member 15on each lateral side. Each front damper housing 17 includes a verticalwall 17A extending upward from a rear part of the front side frame frontpart 4A and an upper wall 17B extending laterally outward from an upperend of the vertical wall 17A and having a laterally outer end joined tothe front upper member 15.

As shown in FIG. 4, each of the left and right front side frame middleparts 4B is provided with a lateral extension 4D that extends laterally.The laterally inner ends of the left and right lateral extensions 4Dlaterally oppose each other via a gap. The laterally outer end of eachof the left and right lateral extensions 4D is joined to an innersurface of the corresponding front side frame middle part 4B. Eachlateral extension 4D has a hat-shaped cross-section opening upward andforms a closed section structure in cooperation with the front floorpanel 7. Each lateral extension 4D constitutes a part of thecorresponding front side frame 4.

As shown in FIGS. 4 and 7, a guide member 19 is provided on a laterallyinner end of each lateral extension 4D. Each guide member 19 extendsrearward from the lower surface of the laterally inner end of thecorresponding lateral extension 4D. The guide member 19 is provided, ina front lower part thereof, with a slanted surface 19A that is slanteddownward toward the rear. Each lateral extension 4D and thecorresponding guide member 19 constitute a rear-end support 21 thatsupports the rear end of the front subframe 6. Each lateral extension 4Dserves as a fastening seat to which the rear end of the front subframe 6is fastened.

As shown in FIGS. 4 and 5, the front subframe 6 includes a pair of leftand right front longitudinal members 23 extending in the fore-and-aftdirection and a front cross member 24 extending laterally to be joinedto each of the front longitudinal members 23. The left and right frontlongitudinal members 23 extend obliquely laterally inward toward therear so as to approach each other toward the rear. Further, thelaterally outer edge of each front longitudinal member 23 is curved suchthat the fore-and-aft central part thereof is recessed laterally inward.

The left and right end portions of the front cross member 24 arerespectively joined to fore-and-aft middle portions of the frontlongitudinal members 23. The left and right end portions of the frontcross member 24 are respectively joined to portions of the frontlongitudinal members 23 slightly forward of the fore-and-aft centersthereof. The front longitudinal members 23 and the front cross member 24each have a closed cross-section. The front edge (front end) of thefront cross member 24 is formed laterally straight. The rear edge of thefront cross member 24 has left and right end portions extending rearwardand laterally outward in an oblique manner. Thereby, the front crossmember 24 has a fore-and-aft width that increases gradually toward thelaterally outward direction.

Behind the front cross member 24, a brace 26 is provided which extendslaterally to connect the left and right front longitudinal members 23.The brace 26 has an X shape in plan view and includes portions extendingfrom the central part thereof in the front left direction, front rightdirection, rear left direction, and rear right direction. The front leftand right end portions of the brace 26 are joined to the left and rightends of the front cross member 24, respectively, and the rear left andright end portions of the brace 26 are joined to the left and rightfront longitudinal members 23, respectively. The brace 26 is preferablyformed of a steel sheet having a vertically facing surface.

As shown in FIG. 4, the front end of each front longitudinal member 23is positioned below the corresponding front side frame front part 4A tobe slightly offset from the same laterally inward. Specifically, alaterally outer part of the front end of the front longitudinal member23 is positioned to overlap a laterally inner part of the front end thefront side frame front part 4A in plan view. Each front longitudinalmember 23 includes, in the front end portion thereof, a front endattachment portion 23A attached to the corresponding front side frame 4.The front end attachment portion 23A is provided in a laterally outerpart of the front end of the front longitudinal member 23. The front endattachment portion 23A of each front longitudinal member 23 and thefront end of the corresponding front side frame front part 4A areconnected to each other by a front connecting member 28 that extendsvertically. Specifically, each front longitudinal member 23 is fastenedto the lower end of the corresponding front connecting member 28 by abolt passed therethrough from below. Each front connecting member 28constitutes a front-end support that supports the front end of the frontsubframe 6. In the present embodiment, the front end attachment portion23A is attached to the front side frame front part 4A indirectly via thefront connecting member 28. In another embodiment, the front endattachment portion 23A may be attached to the front side frame frontpart 4A directly without the front connecting member 28 interposedtherebetween.

The rear end of each front longitudinal member 23 is positioned belowthe corresponding lateral extension 4D. Namely, the rear end of eachfront longitudinal member 23 is positioned more laterally inward thanthe corresponding front side frame middle part 4B. As shown in FIG. 7,the rear end of each front longitudinal member 23 is provided with acollar 29A that vertically extends therethrough. The rear end of thefront longitudinal member 23 is fastened to the lower surface of thelateral extension 4D by a bolt 29B passed through the collar 29A frombelow and threadably engaged with a nut 29C joined to the lateralextension 4D. The rear end of the front longitudinal member 23 protrudesmore rearward than the lateral extension 4D, and the rear edge thereofextends laterally. Further, the rear end of the front longitudinalmember 23 is provided with a vertical width (vertical thickness) thatdecreases gradually toward the rear.

The rear end of the front longitudinal member 23 opposes the slantedsurface 19A of the guide member 19 via a gap in the fore-and-aftdirection. Further, in plan view, the rear end of the front longitudinalmember 23 is positioned to overlap the slanted surface 19A of the guidemember 19.

As shown in FIG. 4, the lower surface of each rear end of the frontlongitudinal member 23 is connected to the lower surface of thecorresponding front side frame middle parts 4B by a plate-shapedconnecting member 27. The connecting member 27 deforms when applied witha load equal to or greater than a predetermined load to release theconnection between the front longitudinal member 23 and the front sideframe middle part 4B.

As shown in FIGS. 1 and 8, a pair of left and right front suspensions 30is provided such that each front suspension 30 is connected to the frontsubframe 6 and the corresponding one of the left and right front sideframes 4. Each front suspension 30 includes a lower arm 31 swingablysupported by the corresponding front longitudinal member 23, a frontknuckle 32 supported by the lower arm 31, and a front shock absorber 33connecting an upper part of the front knuckle 32 and the upper wall 17Bof the corresponding front damper housing 17.

Each lower arm 31 is a so-called A-arm and includes an arm rear part 31Aextending from the rear end forward and laterally outward in an obliquemanner, an arm curved part 31B that is curved laterally outward from thefront end of the arm rear part 31A, and an arm front part 31C extendinglaterally outward from the laterally outer end of the arm curved part31B and supporting the front knuckle 32 at the tip end thereof. The armfront part 31C is formed to have a width larger than those of the armrear part 31A and the arm curved part 31B. On a laterally inner side ofthe arm curved part 31B, a front pivotal support portion 31D is providedto protrude laterally. The front pivotal support portion 31D has an axisthat extends in the fore-and-aft direction. The rear end of the arm rearpart 31A is provided with a rear pivotal support portion 31E having avertically extending axis.

As shown in FIG. 4, each of the left and right front longitudinalmembers 23 is provided with a front lower arm support 36 that supportsthe front pivotal support portion 31D of the lower arm 31 and a rearlower arm support 51 that supports the rear pivotal support portion 31Eof the lower arm 31.

Each front lower arm support 36 is disposed to be generally aligned withthe front cross member 24 laterally, namely, each front lower armsupport 36 is disposed at a position overlapping the front cross member24 in side view and is joined to the corresponding front longitudinalmember 23 and the front cross member 24.

As shown in FIG. 5, each front lower arm support 36 includes a baseportion 36A extending laterally above the corresponding frontlongitudinal member 23 and joined to the front longitudinal member 23and the front cross member 24, and front and rear support walls 36B, 36Ceach joined to the base portion 36A and the front longitudinal member 23and protruding laterally outward from the laterally outer surface of thefront longitudinal member 23.

The base portion 36A is formed in a hollow shape by combining a frontmember and a rear member and is joined to an upper surface and alaterally inner surface of the front longitudinal members 23 and anupper wall of the front cross member 24. The laterally inner end of thebase portion 36A extends through the upper wall of the front crossmember 24 formed in a hollow shape and extends to the interior of thefront cross member 24. The base portion 36A extends from the uppersurface of the front longitudinal member 23 upward and laterally outwardand forms a laterally outer end portion. The laterally outer end portionof the base portion 36A is positioned more laterally outward than thelaterally outer surface of the front longitudinal member 23.

The laterally outer end portion of the base portion 36A is joined to thelower surface of the front side frame front part 4A via a bracket 39.The bracket 39 includes an upper plate portion fastened to the lowersurface of the front side frame front part 4A by a vertically extendingbolt, and a vertical plate portion depending from a laterally inner endof the upper plate portion. The vertical plate portion of the bracket 39contacts a laterally outward-facing end surface of the laterally outerend portion of the base portion 36A and is fastened to the laterallyouter end portion of the base portion 36A by a laterally extending bolt.

An upper part of the base portion 36A forms a slanted portion 36D(connecting portion) that is slanted upwardly from a laterally inner endportion to a laterally outer end portion thereof. Namely, the slantedportion 36D extends in a slanted manner from the front cross member 24to the front side frame front part 4A.

Each of the front and rear support walls 36B, 36C is a plate-like memberhaving a surface facing in the fore-and-aft direction and has alaterally inner edge welded to the laterally outer side of the frontlongitudinal member 23. The rear support wall 36C is positioned behindthe front support wall 36B via a gap. An upper part of the laterallyinner edge of the front support wall 36B extends to above the frontlongitudinal member 23 and is welded to the front face of the baseportion 36A. An upper part of the laterally inner edge of the rearsupport wall 36C extends to above the front longitudinal member 23 andis welded to the rear face of the base portion 36A. A lower part of thelaterally inner edge of each of the front and rear support walls 36B,36C extends to under the front longitudinal member 23 and is welded tothe lower surface of the front longitudinal member 23.

As shown in FIG. 8, the front pivotal support portion 31D of the lowerarm 31 is positioned between the front and rear support walls 36B, 36C.The front pivotal support portion 31D of the lower arm 31 is fitted witha rubber bushing (not shown in the drawings), and a support shaft (notshown in the drawings) is supported on the front and rear support walls36B, 36C so as to extend in the fore-and-aft direction through therubber bushing.

As described above, the front lower arm support 36 includes the baseportion 36A and the front and rear support walls 36B, 36C and swingablysupports the front pivotal support portion 31D of the lower arm 31. Thefront lower arm support 36 is welded to the front longitudinal member 23and the front cross member 24 and is fastened to the front side framefront part 4A via the bracket 39.

As shown in FIG. 4, it is preferred that, in plan view, the frontsupport wall 36B forming the front end of the front lower arm support 36is positioned more forward than the rear end of the lateral end portionof the front cross member 24, and the rear support wall 36C forming therear end of the front lower arm support 36 is positioned more rearwardthan the front end of the front cross member 24. In other words,preferably, the front lower arm support 36 overlaps the front crossmember 24 in side view. In the present embodiment, the front supportwall 36B (the front end of the front lower arm support 36) is positionedmore rearward than the front end of the front cross member 24 and therear support wall 36C (the rear end of the front lower arm support 36)is positioned more forward than the rear end of the front cross member24.

As shown in FIG. 8, a steering gearbox 40 is provided on the uppersurface of the front cross member 24. The steering gearbox 40 includes alaterally extending cylindrical rack housing 41. Inside the rack housing41, a rack shaft 42 is provided to be laterally slidable relative to therack housing 41. The left and right end portions of the rack shaft 42laterally protrude from the rack housing 41 and are connected to theleft and right front knuckles 32 via respective tie rods 43. The rackshaft 42 and each tie rod 43 are connected by a joint 44, which may be aball joint, for example. The left and right joints 44 are arranged inrespective boots 45 which are attached to the left and right ends of therack housing 41, respectively.

At four positions of the front cross member 24; namely, in lateral endportions of the front part of the front cross member 24 and in portionsof the rear part of the front cross member 24 located laterally inwardof the laterally inner end portions of the base portions 36A of the leftand right front lower arm supports 36, collars 47 are provided such thateach collar 47 vertically extends through the front cross member 24 andis welded to the upper wall and the lower wall of the front cross member24. The two collars 47 on the rear side are positioned more laterallyinward than the two collars 47 on the front side.

The lateral end portions of the front part of the rack housing 41 arefastened to the front-side left and right collars 47 provided in thefront cross member 24 by means of bolts. The rear part of the rackhousing 41 is fastened to one of the rear-side left and right collars 47provided in the front cross member 24 by means of a bolt. The shape ofthe rack housing 41 varies depending on the lateral position of thesteering shaft, and one of the rear-side collars 47 to which the rackhousing 41 is fastened is selected in accordance with the shape of therack housing 41. Thus, the rack housing 41 is fastened to the frontcross member 24 at three positions.

The front edge (front end) of each front lower arm support 36 ispositioned more rearward than the front edge (front end) of the frontcross member 24. The laterally inner end portion of the slanted portion36D of each base portion 36A is positioned laterally outward of (to theside of) the upper end of the corresponding rear-side collar 47.

Each rear lower arm support 51 is provided in a part of thecorresponding front longitudinal member 23 between the front lower armsupport 36 and the rear end of the front longitudinal member 23 fastenedto the lateral extension 4D. The rear lower arm support 51 has anopening 51A (see FIGS. 5 and 6) formed in a laterally outer face of thefront longitudinal member 23 and a support shaft (not shown in thedrawings) provided in a deeper side of the opening 51A and extendingvertically to be joined to the upper and lower walls of the frontlongitudinal member 23. The rear pivotal support portion 31E of eachlower arm 31 is fitted with a rubber bushing (not shown in the drawings)through which the support shaft is passed. The rear pivotal supportportion 31E of the lower arm 31 is allowed to move relative to the rearlower arm support 51 by deformation of the rubber bushing. Thereby, eachlower arm 31 is swingably supported to the front subframe 6 by the frontlower arm support 36 and the rear lower arm support 51.

As shown in FIG. 4, in bottom view (or in plan view), the rear lower armsupport 51 on the left side is positioned on an extension line obtainedby extending the left rear end portion of the brace 26. Also, in planview, the rear lower arm support 51 on the right side is positioned onan extension line obtained by extending the right rear end portion ofthe brace 26. The rear lower arm supports 51 are positioned morelaterally inward than the respective front lower arm supports 36.Further, the rear lower arm supports 51 are also positioned morelaterally inward than the left and right joints 44, respectively.

Each front lower arm support 36 is positioned more rearward than thesteering gearbox 40. Each arm front part 31C may extend slightlyobliquely rearward toward the laterally outward direction, and the joint44 on the same lateral side may be provided such that the joint 44 ispositioned on an extension line obtained by extrapolating the arm frontpart 31C in the lengthwise direction when the steering is neutral.

As shown in FIGS. 5 and 6, each front longitudinal member 23 isprovided, in a part thereof forward of the joint with the front crossmember 24, with a deformation promoting portion 53 which has a lowerstiffness than the other part of the front longitudinal member 23. Thedeformation promoting portion 53 is a recess that is formed in the uppersurface of the front longitudinal members 23 to be recessed downward.The deformation promoting portion 53 extends laterally from thelaterally inner surface to the laterally outer face of the frontlongitudinal member 23. When a collision load is applied to the frontlongitudinal member 23 in the fore-and-aft direction, a deformation ofthe front longitudinal member 23 occurs first at the deformationpromoting portion 53, and the front longitudinal member 23 is bentdownward at the deformation promoting portion 53.

A reinforcing plate 54 extends along and is attached to a part of theupper surface of each front longitudinal member 23 located forward ofthe deformation promoting portion 53. A front stabilizer support 56 forrotatably supporting a front stabilizer 55 is provided on eachreinforcing plate 54. The front stabilizer 55 is a rod member includinga laterally extending portion and left and right end portions thatextend rearward from the left and right ends of the laterally extendingportion, respectively. The left and right end portions of the frontstabilizer 55 are joined to the lower ends of the left and right frontshock absorbers 33, respectively, via respective connecting members.Each front stabilizer support 56 is formed with a support hole (notshown in the drawings) through which the laterally extending portion ofthe front stabilizer 55 is passed. A rubber bushing for supporting thelaterally extending portion of the front stabilizer 55 is fitted in thesupport hole of each front stabilizer support 56. Each front stabilizersupport 56 is fastened to the upper surface of the corresponding frontlongitudinal member 23 by means of multiple bolts. A part of each frontlongitudinal member 23 on which the reinforcing plate 54 and the frontstabilizer support 56 are provided is given a higher stiffness than theother part of the same.

As shown in FIGS. 1 and 2, the vehicle body structure 1 includes, as arear structure, a pair of left and right rear side frames 71respectively extending rearward from the rear ends of the left and rightside sills 3 and a rear subframe 72 provided on the underside the rearside frames 71. The rear subframe 72 supports rear wheels 74 via rearsuspensions 73 and also supports an electric motor 75 serving as adriving source for driving the rear wheels 74. In another embodiment,the driving source may be an internal combustion engine.

As shown in FIG. 2, each rear side frame 71 includes a rear side framefront part 71A (kick-up part) extending from the rear end of thecorresponding side sill 3 upward and laterally inward toward the rear inan oblique manner and a rear side frame rear part 71C extending rearwardfrom the rear end of the rear side frame front part 71A via a rear sideframe bent part 71B. Each rear side frame 71 has a lower wall, an innersidewall located on the laterally inner side, an outer sidewall locatedon the laterally outer side, and an upper wall, whereby the rear sideframe 71 has a rectangular closed cross-section.

The left and right rear side frame front parts 71A are joined to eachother by a vehicle body cross member 77 that extends laterally. The leftand right end portions of the vehicle body cross member 77 are joined tolaterally inner surfaces of front parts of the rear side frame frontparts 71A, respectively. A rear floor panel 78 is provided on the upperside of the left and right rear side frames 71 and the vehicle bodycross member 77. The vehicle body cross member 77 has a hat-shapedcross-section opening upward and forms a closed section structure incooperation with the rear floor panel 78. A pair of left and right floormembers 79A are joined to a laterally middle portion of the vehicle bodycross member 77 so as to extend forward along the lower surface of therear floor panel 78. The floor members 79 are formed to have a lowerheight than the vehicle body cross member 77.

As shown in FIGS. 2 and 9, a pair of left and right load transmittingmembers 80 are provided on the rear side of the vehicle body crossmember 77 and on the laterally inner side of the left and right rearside frame front parts 71A, respectively. Each load transmitting member80 is provided in the corner formed by the corresponding rear side framefront part 71A and the vehicle body cross member 77. As shown in FIGS. 9and 10, each load transmitting member 80 includes a bottom wall 80Ahaving a vertically facing surface, a vertical wall 80B extending upwardfrom a laterally inner edge of the bottom wall 80A, and a flange 80Cextending laterally inward from an upper edge of the vertical wall 80B.

The bottom wall 80A has a laterally extending front edge and inner andouter edges that extend obliquely rearward from lateral ends of thefront edge, respectively, so as to approach each other toward the rear,whereby the bottom wall 80A is formed in a triangle. Namely, the bottomwall 80A of each load transmitting member 80 has a lateral width thatincreases gradually toward the front. More specifically, the bottom wall80A is formed in an isosceles triangle, with the inner edge and theouter edge having a substantially same length. The front edge of thebottom wall 80A extends along the lower surface of the vehicle bodycross member 77 and is welded to the lower surface of the vehicle bodycross member 77 at multiple positions. The outer edge of the bottom wall80A extends along the lower surface of the lower wall of the rear sideframe front part 71A and is welded to the lower wall of the rear sideframe front part 71A at multiple positions. The flange 80C is welded tothe lower surface of the rear floor panel 78 at multiple positions. Thevertical wall 80B and the flange 80C extend from the rear end of therear side frame front part 71A forward and laterally inward to the rearface of the vehicle body cross member 77. Each load transmitting member80 forms a closed section structure in cooperation with the rear sideframe front part 71A, the vehicle body cross member 77, and the rearfloor panel 78.

In the closed section structure formed by the load transmitting member80, the rear side frame front part 71A, the vehicle body cross member77, and the rear floor panel 78, at least one partition wall 81 isprovided. In the illustrated embodiment, a single partition wall 81 isprovided. The partition wall 81 has a surface facing in the fore-and-aftdirection, extends laterally, and has a laterally inner end welded tothe vertical wall 80B of the load transmitting member 80 and a laterallyouter end welded to the inner sidewall of the rear side frame front part71A. Further, the partition wall 81 has a lower end welded to the bottomwall 80A of the load transmitting member 80. The laterally inner end,the laterally outer end, and the lower end of the partition wall 81 arepreferably bent to form flanges. In another embodiment, the upper end ofthe partition wall 81 may be welded to the lower surface of the rearfloor panel 78.

As shown in FIG. 2, the rear part of the vehicle body structure 1 isprovided, on each lateral side thereof, with first to fourth vehiclebody-side attachment portions 83 to 86 for attachment of the rearsubframe 72. Each of the left and right first vehicle body-sideattachment portions 83 is provided in a front end portion of thecorresponding rear side frame front part 71A. Each first vehiclebody-side attachment portion 83 is constituted of a through-hole formedin the lower wall of the rear side frame front part 71A and a collar(not shown in the drawings) provided on the upper surface side of thelower wall of the rear side frame front part 71A so as to oppose thethrough-hole. The collar extends vertically inside the rear side framefront part 71A and is welded to the lower wall of the rear side framefront part 71A. Preferably, the collar may also be welded to a partitionwall (not shown in the drawings) provided inside the rear side framefront part 71A. The collar is formed with a female thread in an innerperiphery thereof.

As shown in FIGS. 2, 9, and 13, the left and right second vehiclebody-side attachment portions 84 are respectively provided on the leftand right end portions of the vehicle body cross member 77. The secondvehicle body-side attachment portions 84 are positioned more laterallyinward than the first vehicle body-side attachment portions 83. Eachsecond vehicle body-side attachment portion 84 is constituted of athrough-hole formed in the lower wall of the vehicle body cross member77 and a collar 84A provided on the upper surface side of the lower wallof the vehicle body cross member 77 so as to oppose the through-hole.The collar 84A extends vertically inside the vehicle body cross member77 and is welded to the lower wall of the vehicle body cross member 77.Preferably, the collar 84A may also be welded to a partition wall (notshown in the drawings) provided inside the vehicle body cross member 77.The collar 84A is formed with a female thread in an inner peripherythereof.

As shown in FIGS. 9 and 10, each of the left and right third vehiclebody-side attachment portions 85 is provided on the corresponding loadtransmitting member 80. The left and right third vehicle body-sideattachment portions 85 are arranged at substantially the same lateralpositions as the left and right second vehicle body-side attachmentportions 84, respectively. Each third vehicle body-side attachmentportion 85 is constituted of a through-hole 85A extending verticallythrough the bottom wall 80A of the corresponding load transmittingmember 80 and a collar 85B provided on the upper surface of the bottomwall 80A so as to oppose the through-hole 85A. The collar 85B extendsvertically, has a lower end welded to the upper surface of the bottomwall 80A, and has a side surface welded to the partition wall 81. Thepartition wall 81 is formed with a recess 81A for receiving a side partof the collar 85B. Further, the collar 85B has a flange 85C in the lowerend thereof and is in contact with the bottom wall 80A at the flange85C. The collar 85B is formed with a female thread in an inner peripherythereof.

As shown in FIGS. 2 and 17, each of the left and right fourth vehiclebody-side attachment portions 86 is provided in the rear end of thecorresponding rear side frame rear part 71C. Each fourth vehiclebody-side attachment portion 86 is constituted of a through-hole 86Aformed in the lower wall of the corresponding rear side frame rear part71C and a collar 86B provided on the upper surface side of the lowerwall of the rear side frame rear part 71C so as to oppose thethrough-hole 86A. The collar 86B extends vertically inside the rear sideframe rear part 71C and is welded to the lower wall of the rear sideframe rear part 71C. Further, the collar 86B is welded to a partitionwall 86C provided inside the rear side frame rear part 71C. The collar86B is formed with a female thread in an inner periphery thereof.

As shown in FIGS. 17 and 18, the rear ends of the left and right rearside frame rear parts 71C are joined to a rear panel 88 that extendslaterally to have a surface facing in the fore-and-aft direction. Therear panel 88 is joined to the rear edge of the rear floor panel 78.

The rear subframe 72 includes a pair of left and right rear longitudinalmembers 91 extending in the fore-and-aft direction, and a first rearcross member 92 and a second rear cross member 93 each extendinglaterally and joined to the rear longitudinal members 91. The first rearcross member 92 is positioned forward of the second rear cross member93.

Each of the left and right rear longitudinal members 91, the first rearcross member 92, and the second rear cross member 93 is formed bycombining an upper member (e.g., an upper member 94A constituting thesecond rear cross member 93) having a channel-shaped cross-section thatopens downward and a lower member (e.g., a lower member 94B constitutingthe second rear cross member 93) having a channel-shaped cross-sectionthat opens upward, and has a hollow structure (see FIG. 16). Preferably,the upper member and the lower member include sidewalls having free endsoverlapping each other, and are welded to each other at the overlappingfree ends (see FIG. 15). As shown in FIG. 11, the first rear crossmember 92 has a pair of left and right first longitudinal memberinsertion holes 92A extending therethrough in the fore-and-aftdirection. The second rear cross member 93 has a pair of left and rightsecond longitudinal member insertion holes 93A extending therethrough inthe fore-and-aft direction. Each of the left and right rear longitudinalmembers 91 extends in the fore-and-aft direction to pass through thecorresponding first longitudinal member insertion hole 92A and thecorresponding second longitudinal member insertion holes 93A and iswelded to the first rear cross member 92 and the second rear crossmember 93 in the first longitudinal member insertion hole 92A and thesecond longitudinal member insertion hole 93A. The parts of the firstrear cross member 92 joined to the left and right rear longitudinalmembers 91, namely, the parts around the first longitudinal memberinsertion holes 92A are referred to as first longitudinal member jointportions 92B. Also, the parts of the second rear cross member 93 joinedto the left and right rear longitudinal members 91, namely, the partsaround the second longitudinal member insertion holes 93A are referredto as second longitudinal member joint portions 93B.

As shown in FIGS. 11 and 12, each rear longitudinal member 91 includes arear longitudinal member front part 91A extending rearward and laterallyinward in an oblique manner and a rear longitudinal member rear part 91Cextending rearward from the rear end of the rear longitudinal memberfront part 91A via a rear longitudinal member bent part 91B. The rearlongitudinal member bent part 91B of each rear longitudinal member 91 isjoined to the corresponding first longitudinal member joint portion 92Bof the first rear cross member 92. The rear longitudinal member rearpart 91C extends from the first longitudinal member joint portion 92B ofthe first rear cross member 92 to the second longitudinal member jointportion 93B of the second rear cross member 93. At the front end of eachrear longitudinal member front part 91A, a rear longitudinal memberfront end part 91D is provided which extends laterally outward.

A first rear subframe-side attachment portion 101 is formed in thelaterally outer end of each rear longitudinal member front end part 91D.The first rear subframe-side attachment portion 101 includes a collar101A extending vertically through the rear longitudinal member front endpart 91D. The collar 101A is welded to the upper and lower walls of therear longitudinal member front end part 91D. Each first rearsubframe-side attachment portion 101 is disposed on the underside of thecorresponding first vehicle body-side attachment portion 83 and isfastened to the first vehicle body-side attachment portion 83 by a bolt.

Each rear longitudinal member front part 91A is formed with a secondrear subframe-side attachment portion 102. The second rear subframe-sideattachment portion 102 includes a collar 102A extending verticallythrough the rear longitudinal member front part 91A. The collar 102A iswelded to the upper and lower walls of the rear longitudinal memberfront part 91A. Each second rear subframe-side attachment portion 102 isdisposed on the underside of the corresponding second vehicle body-sideattachment portion 84 and is fastened to the second vehicle body-sideattachment portion 84 by a bolt.

Each of the left and right end portions of the first rear cross member92 is provided with a first extension 92C that extends laterally outwardand upward from the corresponding first longitudinal member jointportion 92B (the corresponding rear longitudinal member 91). Each firstextension 92C has a tip end (laterally outer end) formed with a thirdrear subframe-side attachment portion 103. The third rear subframe-sideattachment portion 103 includes a collar 103A extending verticallythrough the tip end of the first extension 92C. The collar 103A iswelded to the upper and lower walls of the first extension 92C. Eachthird rear subframe-side attachment portion 103 is disposed on theunderside of the corresponding third vehicle body-side attachmentportion 85 and is fastened to the third vehicle body-side attachmentportion 85 by a bolt.

Each of the left and right end portions of the second rear cross member93 is provided with a second extension 93C that extends laterallyoutward and upward from the corresponding second longitudinal memberjoint portion 93B (the corresponding rear longitudinal member 91). Eachsecond extension 93C has a tip end (laterally outer end) formed with afourth rear subframe-side attachment portion 104. The fourth rearsubframe-side attachment portion 104 includes a collar 104A extendingvertically through the tip end of the second extension 93C. The collar104A is welded to the upper and lower walls of the second extension 93C.Each fourth rear subframe-side attachment portion 104 is disposed on theunderside of the corresponding fourth vehicle body-side attachmentportion 86 and is fastened to the fourth vehicle body-side attachmentportions 86 by a bolt. Each of the rear longitudinal members 91 isprovided, in the rear end portion thereof, with a rear-end attachmentportion 91E attached to the corresponding rear side frame 71. Therear-end attachment portion 91E is attached to the rear side frame rearpart 71C indirectly via the second extension 93C of the second rearcross member 93. In another embodiment, the rear-end attachment portion91E may be attached to the rear side frame rear part 71C directly.

Each of the first extensions 92C and the second extensions 93C has avertical width that decreases gradually toward the laterally outwarddirection. Namely, each of the first extensions 92C and the secondextensions 93C becomes thinner toward the tip end.

As shown in FIGS. 14 and 15, the second rear cross member 93 includes anupper surface central part 93D having an upward-facing surface andextending laterally, a pair of left and right upper surface slantedparts 93F extending laterally outward and upward from the left and rightends of the upper surface central part 93D, respectively, via uppersurface bent parts 93E, a lower surface central part 93G having adownward-facing surface and extending laterally, and a pair of left andright lower surface slanted parts 93J extending laterally outward andupward from the left and right ends of the lower surface central part93G, respectively, via lower surface bent parts 93H. The laterally outerends of the upper surface slanted parts 93F and the lower surfaceslanted parts 93J reach the associated fourth rear subframe-sideattachment portions 104. The upper surface central part 93D, the uppersurface bent parts 93E, and the upper surface slanted parts 93F areformed in an upper member 94A constituting the second rear cross member93, while the lower surface central part 93G, the lower surface bentparts 93H, and the lower surface slanted parts 93J are formed in a lowermember 94B constituting the second rear cross member 93.

The left and right upper surface bent parts 93E are positioned laterallyinward of the left and right second longitudinal member joint portions93B, and the left and right lower surface bent parts 93H are positionedlaterally outward of the left and right second longitudinal member jointportions 93B. Thereby, the second rear cross member 93 has the largestvertical width at each of the second longitudinal member joint portions93B. The angle of each upper surface bent part 93E relative to thehorizontal plane is smaller than the angle of each lower surface bentpart 93H relative to the horizontal plane. Each of the lower surfaceslanted parts 93J includes a reinforcing bead 93K extending from thecorresponding lower surface bent part 93H toward the correspondingfourth rear subframe-side attachment portion 104.

As shown in FIG. 1, the rear longitudinal members 91 are positionedlaterally inward of and below the respective rear side frames 71. Inplan view, each rear longitudinal member front part 91A and thecorresponding rear side frame front part 71A are arranged in parallel toeach other, and each rear longitudinal member rear part 91C and thecorresponding rear side frame rear part 71C are arranged in parallel toeach other. The rear side frame bent parts 71B are arranged atsubstantially the same fore-and-aft positions as the rear longitudinalmember bent parts 91B.

Each of the rear side frames 71 is provided with a rear damper mount 112for supporting an upper end of a corresponding rear shock absorber 111.The rear damper mount 112 may constitute a part of a side panel 113forming a rear sidewall of the vehicle 2. Each rear side frame bent part71B and each rear longitudinal member bent part 91B are arranged atpositions overlapping (or generally aligned with) the corresponding reardamper mount 112 in the lateral direction. In other words, the rear sideframe bent part 71B and the rear longitudinal member bent part 91B arepositioned rearward of the front end of the rear damper mount 112 andforward of the rear end of the rear damper mount 112.

Each of the left and right rear longitudinal members 91 is providedwith, from the front side, a first suspension arm support 115, a secondsuspension arm support 116, and a third suspension arm support 117. Thefirst suspension arm support 115 is provided at the boundary between therear longitudinal member front end part 91D and the rear longitudinalmember front part 91A, the second suspension arm support 116 and thethird suspension arm support 117 are provided on the rear longitudinalmember rear part 91C. The first to third suspension arm supports 115-117rotatably support inner ends of first to third suspension arms 121-123,respectively, via rubber bushings. Taking the third suspension arm 123as an example, as shown in FIG. 16, a rubber bushing 123A is provided inthe inner end of the third suspension arm 123, and the rubber bushing123A is supported by a support shaft 117A provided in the thirdsuspension arm support 117. A rear knuckle 124 for rotatably supportingthe corresponding rear wheel 74 is supported at the outer ends of thefirst to third suspension arms 121-123. An upper part of the rearknuckle 124 is connected to the rear damper mount 112 via the rear shockabsorber 111.

As shown in FIG. 1, the lower parts of the left and right rear shockabsorbers 111 are connected to each other by a rear stabilizer 126. Therear stabilizer 126 is a rod member and includes a laterally extendingportion and left and right end portions that extend rearward from theleft and right ends of the laterally extending portion, respectively.The left and right end portions of the rear stabilizer 126 are joined tothe lower ends of the left and right rear shock absorbers 111 viaconnecting members, respectively. The lower surfaces of the left andright rear longitudinal member front parts 91A are each provided with srear stabilizer support 127 for rotatably supporting the laterallyextending portion of the rear stabilizer 126.

As shown in FIGS. 18 and 19, a pair of left and right shock-absorbingstructures 130 that extend rearward are provided at the rear ends of theleft and right rear side frames 71, respectively, via the rear panel 88.Each shock-absorbing structure 130 includes a first shock-absorbingmember 131 and a second shock-absorbing member 132 each extendingrearward from the rear face of the rear panel 88. The secondshock-absorbing member 132 has higher fore-and-aft strength (stiffness)than the first shock-absorbing member 131. The second shock-absorbingmember 132 has a shorter fore-and-aft dimension than the firstshock-absorbing member 131, and the rear end of the secondshock-absorbing member 132 is positioned forward of the rear end of thefirst shock-absorbing member 131.

As shown in FIGS. 19 and 20, the first shock-absorbing member 131 is acrash box constituted of two steel sheets formed in a tubular shapehaving an axis extending in the fore-and-aft direction. The firstshock-absorbing member 131 is formed such that the lateral width at avertically middle part thereof is smaller than each of the lateral widthat an upper part thereof and the lateral width at a lower part thereof.Preferably, the first shock-absorbing member 131 is formed with multiplegrooves and ridges extending laterally or vertically. The rear ends ofthe left and right first shock-absorbing members 131 are joined to arear bumper beam 133 that extends laterally.

Each second shock-absorbing member 132 is positioned inside thecorresponding first shock-absorbing member 131 formed in a tubularshape. In the present embodiment, each second shock-absorbing member 132is constituted of two steel sheets welded to the inner surfaces of leftand right parts of the corresponding first shock-absorbing member 131.The two sheets constituting each second shock-absorbing member 132 areeach bent to have recesses and ridges to define closed sectionstructures in cooperation with the associated first shock-absorbingmember 131. Preferably, the second shock-absorbing members 132 are madeof a material having a higher strength (stiffness) than the firstshock-absorbing members 131.

As shown in FIGS. 12 and 18, the second rear cross member 93 includes aprotrusion 93L that protrudes rearward in a laterally central partthereof. A central part of the lower edge of the rear panel 88 is formedwith a cutout (notch) 88A that is recessed upward (see FIGS. 17 and 19),and the protrusion 93L protrudes through the cutout 88A to the rear ofthe rear panel 88. The rear end of the protrusion 93L is positioned morerearward than the rear ends of the rear side frames 71 and the rearpanel 88 and more forward than the rear ends of the shock-absorbingstructures 130. More specifically, the rear end of the protrusion 93L ispositioned more rearward than the rear ends of the secondshock-absorbing members 132 and more forward than the rear ends of thefirst shock-absorbing members 131. The rear edge of the second rearcross member 93 extends from the protrusion 93L forward and laterallyoutward in an oblique manner toward each of the left and right fourthrear subframe-side attachment portions 104. In the illustratedembodiment, the second rear cross member 93 has a generally arcuateshape in plan view (bottom view) to be concave rearward, and theprotrusion 93L is defined by the concave portion.

As shown in FIG. 21, an electric motor 75 serving as a driving source ismounted on an upper side of the rear subframe 72. The electric motor 75is supported by two mounts 135 provided on the first rear cross member92 and one mount 135 provided on the second rear cross member 93. Eachmount 135 includes s base 135A fastened to the first or second rearcross member 92, 93 and supporting a rubber bushing, and an arm 135Bsupported by the base via the rubber bushing and fastened to theelectric motor 75.

The electric motor 75 is supported on the rear subframe 72 such that therotation axis thereof extends laterally. The driving force of theelectric motor 75 is transmitted to the rear wheels 74 via atransmission mechanism. The electric motor 75 is arranged such that thecenter of gravity G thereof is positioned rearward of the rotation axisO of the rear wheels 74. Namely, the electric motor 75 is placed in arear-end portion of the vehicle 2.

The rear end of the protrusion 93L is positioned rearward of the rearend of the electric motor 75. The upper ends of the shock-absorbingstructures 130 (the first shock-absorbing members 131) are positionedhigher than the lower end of the electric motor 75, and the lower endsof the shock-absorbing structures 130 (the first shock-absorbing members131) are positioned lower than the upper end of the electric motor 75.In other words, as seen in the fore-and-aft direction, theshock-absorbing structures 130 are arranged at positions overlapping theelectric motor 75. Owing to the above arrangement, the load at the timeof a rear collision is not applied directly to the electric motor 75 butis applied the second rear cross member 93 and at least one of theshock-absorbing structures 130.

As shown in FIG. 1, a battery 140 is disposed on the underside of thefront floor panel 7 and the rear floor panel 78. In plan view (bottomview), the battery 140 is positioned in a region surrounded by the leftand right side sills 3, the front subframe 6, and the rear subframe 72.Also, it can be said that the battery 140 is positioned in a regionsurrounded by the left and right side sills 3, the left and right frontside frame inclined parts 4C, the left and right lateral extensions 4D,and the vehicle body cross member 77.

The battery 140 includes multiple battery cells connected to each otherand a battery case containing the multiple battery cells therein. Thebattery case, which serves as an outer shell of the battery 140, issupported by multiple battery support members 143 extending between theleft and right side sills 3.

In the following, the effects and advantages of the aforementionedembodiment will be described. In the vehicle body structure 1 accordingto the embodiment, a load at the time of a frontal collision istransmitted to the left and right side sills 3 via the left and rightfront side frames 4, and the transmission thereof to the battery 140 issuppressed. In addition, the front subframe 6 attached to the front sideframes 4 absorbs the frontal collision load, whereby the loadtransmission to the battery 140 can be suppressed. A load in a rearcollision is transmitted to the left and right side sills 3 via the leftand right rear side frames 71, and the transmission thereof to thebattery 140 is suppressed. Also, the rear subframe 72 attached to therear side frames 71 absorbs the rear collision load, whereby the loadtransmission to the battery 140 can be suppressed. Since the battery 140is positioned in a relatively large region surrounded by the left andright side sills 3, the front subframe 6, and the rear subframe 72, thebattery 140 may have a large size.

The front subframe 6, on which the electric motor 75 is not mounted,breaks away from the rear-end supports 21 and moves downward whenapplied with a collision load, whereby the load transmission from thefront subframe 6 to the battery 140 can be suppressed. Each guide member19 abuts the rear end of the front subframe 6 at the slanted surface 19Athereof and guides the front subframe 6 to move downward in a reliablemanner.

The load transmitting members 80 causes the load applied to the rearside frames 71 from the rear at the time of a rear collision to bedispersed to the side sills 3 and the vehicle body cross member 77, suchthat the deformation of the rear side frames 71 can be suppressed.Thereby, the rear side frames 71 can resist to the load at the time of arear collision, and the electric motor 75 mounted on the rear subframe72 can be protected properly. Each load transmitting member 80 forms aclosed section structure in cooperation with the corresponding rear sideframe 71 and the rear floor panel 78 such that the stiffness of the loadtransmitting member 80 is improved. The stiffness of the loadtransmitting member 80 is also improved by the partition wall 81 and thecollar 85B. Thus, the load transmitting members 80 are provided withrelatively high stiffness, and the third vehicle body-side attachmentportions 85 are provided in these load transmitting members 80, wherebythe rear subframe 72 can be supported highly stably. Because each loadtransmitting member 80 has a lateral width that increases graduallytoward the front, the load applied to the rear side frames 71 can bedispersed over a wide range of the vehicle body cross member 77 owing tothe load transmitting members 80.

A lateral load input from the first to third suspension arms 121-123 tothe rear longitudinal members 91 is transmitted to the load transmittingmembers 80 and the rear side frames 71 via the first and secondlongitudinal member joint portions 92B, 93B, the first and secondextensions 92C, 93C, and the third and fourth rear subframe-sideattachment portions 103, 104 in this order. Therefore, the stiffness ofthe rear subframe 72 against the lateral load input from the suspensionarms can be improved.

Since the second rear cross member 93 has the largest vertical width ateach of the second longitudinal member joint portions 93B, the rearlongitudinal members 91 can be supported reliably. Thereby, the rearlongitudinal members 91 can sufficiently resist a relatively largelateral force in an early stage of the load input. Since the verticalwidth of each second extension 93C decreases gradually toward thelaterally outward direction, the concentration of stress on the secondextension 93C can be suppressed. By making the bend of the upper surfacebent parts 93E more gentle than the bend of the lower surface bent parts93H, the lateral force applied from the rear longitudinal members 91 tothe second rear cross member 93 can be transmitted efficiently to therear side frames 71.

The left and right front longitudinal members 23 of the front subframe 6extend obliquely so as to approach each other toward the rear, andtherefore, the load applied to the front subframe 6 at the time of afrontal collision can be transmitted in an inward direction obliquelyrelative to the left and right front side frames 4, whereby the load canbe dispersed.

If a load is applied to the front longitudinal members 23 at the time ofa frontal collision, the front longitudinal members 23 bend downward atthe respective deformation promoting portions 53. As a result, stress isapplied to the rear-end supports 21 and the bolts 29B, and the fasteningstructure between the rear end of each front longitudinal member 23 andthe corresponding rear-end support 21 is disrupted so that the frontsubframe 6 can break away from the rear-end support 21 smoothly. Sincethe reinforcing plate 54, the front stabilizer support 56, the frontcross member 24, and the front lower arm support 36 are provided infront of and behind each deformation promoting portion 53, the stiffnessof the deformation promoting portion 53 is relatively low. Thereby, thestress tends to concentrate on the deformation promoting portion 53, andthus, the deformation preferentially starts from the deformationpromoting portion 53.

Since the rear side frame bent parts 71B are positioned to a lateralside of the corresponding rear damper mounts 112, the rear side framebent parts 71B are reinforced by the rear damper mounts 112, and therear side frame bent parts 71B are made resistant to bending under theload at the time of a rear collision.

Because the rear ends of the shock-absorbing structures 130 protrudemore rearward than the rear end of the rear subframe 72 (the protrusion93L), the rear subframe 72 receives the load at the protrusion 93Lthereof after the shock-absorbing structures 130 absorb the load.Therefore, when the collision load is relatively small, the load isabsorbed by the deformation of the shock-absorbing structures 130 and isprevented from being easily transmitted to the rear subframe 72. Thus,the deformation of the rear subframe 72 is suppressed. On the otherhand, when the collision load is large, the load is transmitted from theprotrusion 93L to the rear subframe 72 so that the load applied to therear side frames 71 can be dispersed.

When the collision load is relatively small, the load is absorbed by thefirst shock-absorbing members 131, and when the collision load is large,the load is absorbed by the second shock-absorbing members 132. Becausethe shock-absorbing structures 130 are positioned more rearward than theelectric motor 75, the load at the time of a rear collision is appliedto the electric motor 75 after being absorbed by the shock-absorbingstructures 130.

Because the protrusion 93L of the second rear cross member 93, whichforms the rear end of the rear subframe 72, is positioned more rearwardthan the rear end of the electric motor 75, a load in a rear collisionis more likely to be applied to the rear subframe 72 than to theelectric motor 75. Since the electric motor 75 is disposed on the rearpart of the rear subframe 72, it is possible to secure a space in frontof the electric motor 75. High voltage devices, such as a converter, canbe mounted in the space. In addition, this space can be used as a space(escape space) into which the electric motor 75 can move at the time ofa rear collision, whereby the collision between the battery 140 and theelectric motor 75 can be suppressed. The cutout 88A provided in thelower edge of the rear panel 88 allows the protrusion 93L of the rearsubframe 72 to protrude to the rear of the rear panel 88 withoutinterfering with the rear panel 88.

By positioning the rear end of the protrusion 93L rearward of the rearends of the rear side frames 71, the electric motor 75 can be disposedat a more rearward position in the vehicle body structure 1 so that aspace can be secured in front of the electric motor 75. In addition, theload applied to the rear side frames 71 due to rear collision can betransmitted from the protrusion 93L to the rear subframe 72 so that theload applied to the rear side frames 71 can be dispersed.

Since the rear edge of the second rear cross member 93 extends from theprotrusion 93L forward and laterally outward in an oblique manner towardeach of the left and right fourth rear subframe-side attachment portions104, the load applied to the central part of the second rear crossmember 93 from the rear can be transmitted efficiently to the left andright rear side frames 71.

The protrusion 93L of the rear subframe 72 is positioned forward of therear ends of the shock-absorbing structures 130 and rearward of thefront ends of the same, the second rear cross member 93 receives theload at the protrusion 93L after the shock-absorbing structures 130absorbs the load. Therefore, a relatively small collision load isabsorbed by the shock-absorbing structures 130 and is prevented frombeing easily transmitted to the rear subframe 72. Thereby, thedeformation of the rear subframe 72 is suppressed. On the other hand,when the collision load is large, the load is transmitted from theprotrusion 93L to the rear subframe 72 so that the load applied to therear side frames 71 can be dispersed.

The front subframe 6 in the present embodiment has the front lower armsupports 36 at parts thereof having an improved stiffness owing to thefront cross member 24. Therefore, although the front longitudinalmembers 23 include the deformation promoting portions 53 and have acurved shape to widen a steering space for the front wheels 5, the frontsubframe 6 can be made resistant to deformation under a lateral forceapplied thereto via either lower arm 31. Thereby, ride comfort anddriving performance can be improved. Because the front longitudinalmembers 23 can be curved laterally inward so that wide spaces in whichthe front wheels 5 are steered can be secured on laterally outer sidesof the front subframe 6, it is possible to achieve a large steeringangle range of the front wheels 5.

Because the front lower arm supports 36 are provided at portions of thefront subframe 6 overlapping the front cross member 24 in the lateraldirection, the front subframe 6 can be made even more resistant todeformation under the lateral force applied via either lower arm 31.

Since each front lower arm support 36 is joined to the correspondingfront longitudinal member 23 and the front cross member 24, thestiffness of the front lower arm support 36 is improved. Thereby, thefront subframe 6 can support the lower arms 31 reliably. In addition,this increases the difference in stiffness between the deformationpromoting portion 53 of each front longitudinal member 23 and the partof the front longitudinal member 23 rearward of the deformationpromoting portion 53 where the front cross member 24 and the front lowerarm support 36 are provided, and therefore, the front longitudinalmember 23 can deform reliably at the deformation promoting portion 53 atthe time of a frontal collision.

Since each front lower arm support 36 is joined to the correspondingfront side frame 4, the stiffness of the front lower arm support 36 isimproved even further. In addition, the lateral force applied to thefront lower arm support 36 from the corresponding lower arm 31 can betransmitted to the front side frame 4. Moreover, the slanted portion 36Dof each front lower arm support 36 allows the load to be transmittedefficiently from the front longitudinal member 23 and the front crossmember 24 to the front side frame 4. An end of the slanted portion 36Dis positioned at a part of the front cross member 24 having stiffnessimproved by the collar 47, and therefore, the load can be transmittedefficiently from the front cross member 24 to each front side frame 4.Further, the steering gearbox 40 contributes to improving the stiffnessof the front cross member 24.

The brace 26 improves the stiffness of the front subframe 6. Likewise,the front stabilizer 55 improves the stiffness of the front subframe 6.Owing to these features, the front subframe 6 can be made resistant todeformation under the lateral force applied thereto via either lower arm31.

At the time of frontal collision, the front crash boxes 12 deform firstto absorb the load, and therefore, when the collision load is small, thedeformation promoting portion 53 is prevented from deforming. Thereby,replacement of the front subframe 6 can be avoided.

Concrete embodiments of the present invention have been described in theforegoing, but the present invention should not be limited by theforegoing embodiments and various modifications and alterations arepossible within the scope of the present invention.

The invention claimed is:
 1. A vehicle bodl3y rear structure,comprising: a pair of left and right rear side frames extending in afore-and-aft direction in a rear part of a vehicle; a rear subframeattached to the rear side frames and supporting rear wheels via rearsuspensions and an electric motor serving as a driving source fordriving the rear wheels; and a pair of left and right shock-absorbingstructures respectively provided at rear ends of the rear side framesand extending rearward, wherein the rear subframe includes a pair ofleft and right rear subframe longitudinal members extending in thefore-and-aft direction and a rear subframe cross member extendinglaterally and joined to the left and right rear subframe longitudinalmembers, the rear subframe cross member includes a protrusion thatprotrudes rearward in a laterally central part thereof, and a rear endof the protrusion is positioned more rearward than the rear ends of therear side frames and rear end of the electric motor, and more forwardthan rear ends of the shock-absorbing structures.
 2. The vehicle bodyrear structure according to claim 1, wherein each shock-absorbingstructure includes a first shock-absorbing member extending rearwardfrom the rear end of the corresponding rear side frame and a secondshock-absorbing member extending rearward from the rear end of thecorresponding rear side frame and having a fore-and-aft strength higherthan that of the first shock-absorbing member, rear ends of the secondshock-absorbing members are positioned more forward than rear ends ofthe first shock-absorbing members, and the rear end of the protrusion ispositioned more forward than the rear ends of the second shock-absorbingmembers.
 3. The vehicle body rear structure according to claim 2,wherein each first shock-absorbing member consists of a crash boxextending rearward from the rear end of the corresponding rear sideframe and having a rear end joined to a laterally extending bumper beam.4. The vehicle body rear structure according to claim 1, furthercomprising a driving source for driving rear wheels, the driving sourcebeing mounted on an upper side of the rear subframe, wherein upper endsof the shock-absorbing structures are positioned higher than a lower endof the driving source, and lower ends of the shock-absorbing structuresare positioned lower than an upper end of the driving source.
 5. Thevehicle body rear structure according to claim 1, wherein a rear edge ofthe rear subframe cross member extends from the protrusion forward andlaterally outward in an oblique manner toward each of the left and rightrear side frames.
 6. A vehicle body rear structure, comprising: a pairof left and right rear side frames extending in a fore-and-aft directionin a rear part of a vehicle; a rear subframe attached to the rear sideframes; and a pair of left and right shock-absorbing structuresrespectively provided at rear ends of the rear side frames and extendingrearward, wherein the rear subframe includes a pair of left and rightrear subframe longitudinal members extending in the fore-and-aftdirection and a rear subframe cross member extending laterally andjoined to the left and right rear subframe longitudinal members, therear subframe cross member includes a protrusion that protrudes rearwardin a laterally central part thereof, a rear edge of the rear subframecross member extends from the protrusion forward and laterally outwardin an oblique manner toward each of the left and right rear side frames,and a rear end of the protrusion is positioned more rearward than therear ends of the rear side frames and more forward than rear ends of theshock-absorbing structures.
 7. The vehicle body rear structure accordingto claim 6, wherein each shock-absorbing structure includes a firstshock-absorbing member extending rearward from the rear end of thecorresponding rear side frame and a second shock-absorbing memberextending rearward from the rear end of the corresponding rear sideframe and having a fore-and-aft strength higher than that of the firstshock-absorbing member, rear ends of the second shock-absorbing membersare positioned more forward than rear ends of the first shock-absorbingmembers, and the rear end of the protrusion is positioned more forwardthan the rear ends of the second shock-absorbing members.
 8. The vehiclebody rear structure according to claim 7, wherein each firstshock-absorbing member consists of a crash box extending rearward fromthe rear end of the corresponding rear side frame and having a rear endjoined to a laterally extending bumper beam.
 9. The vehicle body rearstructure according to claim 6, further comprising a driving source fordriving rear wheels, the driving source being mounted on an upper sideof the rear subframe, wherein upper ends of the shock-absorbingstructures are positioned higher than a lower end of the driving source,and lower ends of the shock-absorbing structures are positioned lowerthan an upper end of the driving source.